2016 FSA Posters

P001: DEXMETOMIDINE AS AN ADDITIVE TO POPLITEAL NERVE BLOCK : A PILOT STUDY EXAMINING ANALGESIC EFFECT AND PATIENT SATISFACTION
Geetha Kannan, MD, Alberto Ardon, MD, MPH; University of Florida-Jacksonville

Introduction: Several adjunct agents have been investigated as a way to prolong the duration of peripheral nerve blocks. Clinical studies have recently suggested that the alpha-2 agonist dexmedetomidine may improve block duration and patient analgesia. Based on these studies and thus far lack of evidence of neurological harm, our regional anesthesia team has begun to utilize dexmedetomidine as an additive to some nerve blocks. The purpose of this study was to provide objective data and to serve as a pilot study to determine if a larger prospective trial is warranted to examine the prolongation of analgesia provided by dexmedetomidine when added to popliteal nerve blocks. Our hypothesis was that dexmedetomidine will prolong time to first analgesic and improve patient satisfaction with peripheral nerve blockade.

Methods: A total of 32 patient charts were reviewed for this retrospective study: 16 patients who had a popliteal nerve block with ropivacaine only (Group R) and 16 patients who received a popliteal nerve block with ropivacaine and 20mcg of dexmedetomidine (Group RD). All patients received 25-30ml of 0.5% ropivacaine; all underwent foot/ankle surgery by the orthopedic service. Outcome variables were obtained from patient electronic charts and follow-up documentation as recorded by the acute pain service. The primary outcome of this study was time to first analgesic (in hours). Secondary outcomes included duration of motor block (in hours) and patient satisfaction score (0-10). Written informed consent was not required by local IRB.

Results: Mean time-to-first-analgesic was significantly longer for the dexmedetomidine patients (23.66 ± 3.60 vs 8.97 ± 1.95, p<0.001 [mean ± SD]). Mean duration of motor block was also much longer in Group RD (24.30 ± 3.0 vs 11.0 ± 2.8, p<0.001). Mean patient satisfaction was 9.75 ± 0.68 in Group RD vs 7.81 ± 1.22 in Group R, p<0.001. No patient reported any complications or a block lasting more than 48 hours.

Conclusion: The addition of 20mcg of dexmedetomidine to a popliteal nerve block prolonged time-to-first-analgesic and improved patient satisfaction. The results of this pilot study support the possible role of dexmedetomidine as a block adjunct. However, dexmedetomidine also significantly prolonged motor blockade. A larger prospective, randomized, double-blind study is warranted.